| Message ID | 20250130171614.1657224-2-marcus.wichelmann@hetzner-cloud.de (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | XDP metadata support for tun driver | expand |
On 01/30, Marcus Wichelmann wrote: > Enable the support for bpf_xdp_adjust_meta for XDP buffers initialized > by the tun driver. This is useful to pass metadata from an XDP program > that's attached to a tap device to following XDP/TC programs. > > When used together with vhost_net, the batched XDP buffers were already > initialized with metadata support by the vhost_net driver, but the > metadata was not yet passed to the skb on XDP_PASS. So this also adds > the required skb_metadata_set calls. Can you expand more on what kind of metadata is present with vhost_net and who fills it in? Is it virtio header stuff? I wonder how you want to consume it.. Can you also add a selftest to use this new functionality? > Signed-off-by: Marcus Wichelmann <marcus.wichelmann@hetzner-cloud.de> > --- > drivers/net/tun.c | 23 ++++++++++++++++++----- > 1 file changed, 18 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index e816aaba8..d3cfea40a 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -1600,7 +1600,8 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile, > > static struct sk_buff *__tun_build_skb(struct tun_file *tfile, > struct page_frag *alloc_frag, char *buf, > - int buflen, int len, int pad) > + int buflen, int len, int pad, > + int metasize) > { > struct sk_buff *skb = build_skb(buf, buflen); > > @@ -1609,6 +1610,8 @@ static struct sk_buff *__tun_build_skb(struct tun_file *tfile, > > skb_reserve(skb, pad); > skb_put(skb, len); > + if (metasize) > + skb_metadata_set(skb, metasize); > skb_set_owner_w(skb, tfile->socket.sk); > > get_page(alloc_frag->page); > @@ -1668,6 +1671,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, > char *buf; > size_t copied; > int pad = TUN_RX_PAD; > + int metasize = 0; > int err = 0; > > rcu_read_lock(); > @@ -1695,7 +1699,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, > if (hdr->gso_type || !xdp_prog) { > *skb_xdp = 1; > return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, > - pad); > + pad, metasize); > } > > *skb_xdp = 0; > @@ -1709,7 +1713,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, > u32 act; > > xdp_init_buff(&xdp, buflen, &tfile->xdp_rxq); > - xdp_prepare_buff(&xdp, buf, pad, len, false); > + xdp_prepare_buff(&xdp, buf, pad, len, true); > > act = bpf_prog_run_xdp(xdp_prog, &xdp); > if (act == XDP_REDIRECT || act == XDP_TX) { > @@ -1730,12 +1734,16 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, > > pad = xdp.data - xdp.data_hard_start; > len = xdp.data_end - xdp.data; > + > + metasize = xdp.data - xdp.data_meta; [..] > + metasize = metasize > 0 ? metasize : 0; Why is this part needed?
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index e816aaba8..d3cfea40a 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1600,7 +1600,8 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile, static struct sk_buff *__tun_build_skb(struct tun_file *tfile, struct page_frag *alloc_frag, char *buf, - int buflen, int len, int pad) + int buflen, int len, int pad, + int metasize) { struct sk_buff *skb = build_skb(buf, buflen); @@ -1609,6 +1610,8 @@ static struct sk_buff *__tun_build_skb(struct tun_file *tfile, skb_reserve(skb, pad); skb_put(skb, len); + if (metasize) + skb_metadata_set(skb, metasize); skb_set_owner_w(skb, tfile->socket.sk); get_page(alloc_frag->page); @@ -1668,6 +1671,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, char *buf; size_t copied; int pad = TUN_RX_PAD; + int metasize = 0; int err = 0; rcu_read_lock(); @@ -1695,7 +1699,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, if (hdr->gso_type || !xdp_prog) { *skb_xdp = 1; return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, - pad); + pad, metasize); } *skb_xdp = 0; @@ -1709,7 +1713,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, u32 act; xdp_init_buff(&xdp, buflen, &tfile->xdp_rxq); - xdp_prepare_buff(&xdp, buf, pad, len, false); + xdp_prepare_buff(&xdp, buf, pad, len, true); act = bpf_prog_run_xdp(xdp_prog, &xdp); if (act == XDP_REDIRECT || act == XDP_TX) { @@ -1730,12 +1734,16 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, pad = xdp.data - xdp.data_hard_start; len = xdp.data_end - xdp.data; + + metasize = xdp.data - xdp.data_meta; + metasize = metasize > 0 ? metasize : 0; } bpf_net_ctx_clear(bpf_net_ctx); rcu_read_unlock(); local_bh_enable(); - return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, pad); + return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, pad, + metasize); out: bpf_net_ctx_clear(bpf_net_ctx); @@ -2452,6 +2460,7 @@ static int tun_xdp_one(struct tun_struct *tun, struct sk_buff_head *queue; u32 rxhash = 0, act; int buflen = hdr->buflen; + int metasize = 0; int ret = 0; bool skb_xdp = false; struct page *page; @@ -2467,7 +2476,6 @@ static int tun_xdp_one(struct tun_struct *tun, } xdp_init_buff(xdp, buflen, &tfile->xdp_rxq); - xdp_set_data_meta_invalid(xdp); act = bpf_prog_run_xdp(xdp_prog, xdp); ret = tun_xdp_act(tun, xdp_prog, xdp, act); @@ -2507,6 +2515,11 @@ static int tun_xdp_one(struct tun_struct *tun, skb_reserve(skb, xdp->data - xdp->data_hard_start); skb_put(skb, xdp->data_end - xdp->data); + metasize = xdp->data - xdp->data_meta; + metasize = metasize > 0 ? metasize : 0; + if (metasize) + skb_metadata_set(skb, metasize); + if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun))) { atomic_long_inc(&tun->rx_frame_errors); kfree_skb(skb);
Enable the support for bpf_xdp_adjust_meta for XDP buffers initialized by the tun driver. This is useful to pass metadata from an XDP program that's attached to a tap device to following XDP/TC programs. When used together with vhost_net, the batched XDP buffers were already initialized with metadata support by the vhost_net driver, but the metadata was not yet passed to the skb on XDP_PASS. So this also adds the required skb_metadata_set calls. Signed-off-by: Marcus Wichelmann <marcus.wichelmann@hetzner-cloud.de> --- drivers/net/tun.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-)